The present application generally relates to a stepped attenuation circuit with constant decibel (dB) steps that can be used in an electronic device, such as an amplifier or attenuator.
Amplifiers or attenuators with equal dB steps of gain or attenuation can be useful in communications devices. Typical implementations of equal dB steps in an amplifier or attenuator can use either: 1) complicated switching arrangements with a few different resistor values; or 2) a simple switching arrangement with many different resistor values.
In one example, a stepped amplifier or attenuator can be made by selecting among N different, two-resistor stages to provide N different gains, which can require 2 N different resistor values and either a 1-pole, N throw switch or a 2-pole, N throw switch. In another example, the stepped amplifier or attenuator can be made by constructing a series or string of N resistors to produce different values of gain or attenuation, which may require N different resistor values and a 1-pole, N throw switch. In a further example, the stepped amplifier or attenuator can be made by constructing a line of pi or T sections switched by double pole, double throw switches. Some common shortcomings of the above-identified configurations are that they require either a complex switching arrangement or many different resistor values.